Conclusion
Our study concluded that the encroachment of both Leguminosae and Non-Leguminosae shrubs had the overall facilitation impacts on ecosystem functioning of the semi-arid alpine steppe. However, our finding showed divergent above- and belowground ecosystem functioning responses to both Leguminosae and Non-Leguminosae shrubs encroachment in the Tibetan semi-arid alpine steppes, with the BEMF index rather than AEMF index of semi-arid alpine steppes increased following shrub encroachment. We highlight the role of shrub encroachment induced enhancements in resources availability, such as increased soil nutrients, maybe of more importance for determining their impacts on ecosystem functioning in semi-arid alpine steppes. Our findings could help provide new insights for the further understanding of alpine ecosystem transformations, and are beneficial for scientific management and utilization of semi-arid alpine steppes.